1. Field of the Invention
The present invention relates to a soft-magnetic multilayer thin film for use in a thin-film magnetic head for high-density magnetic recording, and also relates to a method of manufacturing the same.
2. Description of the Prior Art
As a soft-magnetic layer of a thin-film magnetic core to be used in a HDD (Hard Disk Drive)-oriented thin-film magnetic head for magnetically recording data with high density, a Permalloy magnetic thin film produced by an electroplating method has been most widely used, conventionally. The manufacturing method by electroplating has been hitherto utilized taking the advantage of its capability of enhancing accuracy of soft-magnetic thin-film magnetic core patterns. However, an electroplating method, as applied to thin-film magnetic head cores, has been limited to applications to a Permalloy (Ni-Fe alloy) magnetic thin film because of its difficulty in alloy plating. In this connection, it has been revealed that, with use of a large amount of electric current for alloy plating, it is possible to obtain multi-element soft-magnetic alloy thin films, composed of such as Co-Fe-Cr, Fe-Co-Ni-Cr alloy and the like through electroplating method, which the soft-magnetic alloy thin films are high enough in saturation magnetic flux density to be suitable for high-density recording magnetic heads.
A Permalloy magnetic thin film produced by the electroplating method or multi-element soft-magnetic alloy thin films with high saturation magnetic flux density obtainable by the electroplating method, in particular, plating with use of a large amount of electric current as above mentioned have been involved with problems as following. That is, there occur minute depressions or protruded abnormally grown spots on the thin film surface due to hydrogen foaming or the like, which may adversely affect the magnetic characteristics, for example by causing the coercive force of magnetic core thin-film layers to increase, or obstructing the movement of magnetic domain walls.
Meanwhile, it is known that a multilayer film structure at least magnetically isolated in the direction of film thickness of the thin film is effective to enhance the high-frequency characteristic and to prohibit the magnetic domain structure of a magnetic core from being subdivided within the thin-film plane, based on the magnetic domain evaluation of laminated-film cores composed of a soft-magnetic thin film such as of Permalloy and a thin non-magnetic layer obtained by deposition. However, any practical method has not been known yet by which the whole multilayer film can be prepared through electroplating.